1. Field of the Invention
The present invention relates to broadband switching networks based on a broadband ISDN using ATM (Asynchronous Transfer Mode) technologies for use in companies.
2. Description of the Related Art
Efforts for integrating individual service networks such as telephone networks, data networks, FAX networks, and so forth which have been developed and constructed over 100 years of history into one network system with ISDN (Integrated Services Digital Network) have been made throughout the world.
As the first step for constructing the ISDN system, narrow band ISDN systems have been operated in advanced countries including Japan since 1988. In addition, besides integration with a broadcasting network by using a broadband ISDN based on the ATM technologies, the engineering developments of the ISDN network have been initiated by CCITT (International Telegraph and Telephone Consultative Committee) and promoted in major laboratories in the world.
On the way of introduction, development, and popularization of the broadband ISDN for use in companies, it can be estimated that small capacity systems on the order of several ten of terminal equipments to several hundreds of terminal equipments as initial installations will be expanded to large capacity systems of for example 16000 terminal equipment.
Thus, from the standpoint of cost required for the expansion, a consistent architecture is preferable for the broadband switching network for use in companies.
However, thus far, a broadband switching network with a consistent architecture has not been proposed. Thereby, the broadband ISDN for use in companies has not been satisfactorily introduced.
As was described above, since the architecture of the systems has not been consistent in the introduction stage, the development stage, and the popularization stage, equipment which has been introduced cannot be effectively used for expanding the systems and thereby result in many losses.